Heat is generated during the material removal when grinding a work piece to a desired measure between a grinding wheel and a regulating wheel. In addition to the heat, the centerless grinding machine also produces a lot of grinding chips and/or particles which are removed during the grinding process. In order to control the heat generation as well as the generation of debris produced by the centerless grinding machine normally a coolant is applied to the machine in order to cool the components of the centerless grinding machine and also to carry away the debris generated by the grinding process.
The heat generation results in unwanted thermal expansion of various components and structure of the centerless grinding machine which can affect the final accuracy of the ground dimensions of the work piece. In addition, the debris can be detrimental to moving components of the centerless grinding machine; in particular metallic particles are extremely detrimental to the operation of electro magnetic linear motors. Fluids and coolants naturally flow downwardly due to gravity and therefore coolant is normally applied from above and collected below. Unfortunately most of the complex drive components and drive systems of conventional centerless grinding machines are also mounted below the grinding and regulating wheels. The conventional method of mounting and driving the grinding wheel and the regulating wheel makes it very difficult to utilize electromagnetic linear drive systems since they potentially are most vulnerable to penetration of coolant and the debris and particles entrained within the coolant, thereby negatively impacting the efficiency and accuracy of the electromagnetic linear drive systems mounted in the conventional manner and locations.
U.S. Pat. No. 5,558,567 filed by Olle Hedberg on Feb. 14, 1995 and which issued on Sep. 24, 1996 under the title Centerless Machines, describes a centerless grinding machine which attempts to minimize the thermal deviation created in the centerless grinding process. In particular the specification describes a grinding carriage and a regulating carriage which is arranged in an overlap relation, such that one supporting point of one of the carriage is situated between two supporting points of the other carriage thereby compensating thermally dependent length variations of the carriages. This specification also describes the possibility of using electromagnetic linear motors.
The Hedberg specification however does not discuss how the flow of coolant and/or the structure can be optimized in order to minimize thermal variations and errors, or how the electromagnetic linear motors can be arranged in such a manner in order to minimize the impregnation of particles and debris into the linear motors.